3 9 4 METALLURGY 



considerable success as an electric resistance heater at high temperature; the newest grade 

 of this alloy is claimed to withstand continuous heating at nooC. An alloy of chromium 

 and cobalt is described as having a white colour and being practically incorrodible, being 

 unattacked even by nitric acid. It is said to have the hardness of steel and to take a cutting 

 edge. Its incorrodibility indicates that the material would be particularly useful for such 

 purposes as fruit knives and table cutlery. Its use for razors is also suggested, but it remains 

 to be ascertained whether it shares the tendency of modern high-speed tool steels to produce 

 undesirable symptoms in any small wounds inflicted. 



Physics and Physical Chemistry. The period under review has been particularly rich 

 in scientific investigations on metals and alloys which come under the heading of 

 " Metallography " in the wider sense of that word, but this sense has now become so 

 wide that " Physical Metallurgy " is a preferable name for the rapidly expanding science, 

 which now embraces the study of all the physical properties as well as the physico- 

 chemical relations of metals and alloys. Typical of this development is the existence, 

 since 1911, of an " International Journal of Metallography " published in Berlin, and the 

 rapid rise of the Institute of Metals, founded in England in 1910. The wide-spread 

 activity in this subject is also typified by the fact that, in a report on progress presented 

 by Heyn to the International Association for Testing Materials, references are given 

 to over 500 papers bearing dates later than 1909. 



The equilibrium diagram of the iron-carbon system has been the subject of continued 

 research and controversy on minor points, but the main features of the diagram are 

 now accepted by all except a few extremists. Among researches bearing upon it the 

 work of Gutowsky may be mentioned which indicates the necessity of revising the posi- 

 tion of the " solidus " curve for the low-carbon end of the diagram. Rosenhain and 

 Humfrey have demonstrated the existence of a relatively hard modification of iron above 

 the critical points, while Baykoff has shown by means of etching with gaseous hydro- 

 chloric acid at high temperatures that steel is a homogeneous solid solution at those 

 temperatures, as required by the accepted diagram. Controversy and difficulty still 

 centre around the true relations of graphite and cementite, and the names of Ruff and 

 Goecke, Ruer and Iljyn and Hanemann are associated with important work on this 

 question. Another important step in the metallography of steel is denoted by the adop- 

 tion, at the recent New York Congress of the International Association for Testing 

 Materials, of a uniform nomenclature for the microscopic constituents of iron and steel. 

 The fact that Howe and Sauveur have been able to prepare such a report indicates that 

 a substantial agreement has now been reached by the majority of the world's leading 

 experts. Increased attention has also been given to the foreign bodies, such as slag, 

 sulphides and silicates of manganese and iron etc., which are met with in steel. Recent 

 research is summarised in a report to the above-named Congress by Rosenhain. 



Copper and its alloys have received much attention. In the copper-zinc series (brass) 

 Carpenter has drawn attention to a thermal point at 470 C. and has demonstrated its 

 nature, as a decomposition of the |3 into the a and 7 phases, in an elaborate series of 

 papers. The constitution of copper-arsenic alloys (Hudson) and of the phosphor- 

 bronzes (Law) has also been studied. The Ninth Report to the Alloys Research Com- 

 mittee of the Institution of Mechanical Engineers (London) contains an elaborate study 

 of the ternary group of alloys of copper with aluminium and manganese, and a detailed 

 metallographic study of portions of the system (Rosenhain and Lantsberry). This 

 attack on the problem of the constitution of ternary systems of alloys is typical of a very 

 large amount of work which has been undertaken, principally in Germany, during the 

 past two years. Most of this work, however, although of great interest as yielding u 

 first rough idea of the constitutions of these systems, must be regarded as strictly pre- 

 liminary, since the methods and apparatus used are in many cases in adequate for the 

 complete study of such complex problems. The manner in which early investigations of 

 alloys are apt to be inaccurate has recently been illustrated in the aluminium-zinc sys- 

 tem, where a research carried out with the greatest available refinements has led to a 

 complete revision of the formerly accepted diagram (Rosenhain and Archbutt). 



Many other fields of enquiry which have begun to yield important results can only 



